5 research outputs found
Onto the sense of smell in macaws, amazons and toucans: can they use volatile cues of fruits to make foraging decisions?
Over the past decades, empirical evidence has been accumulated indicating that olfactory information plays a fundamental role in bird life history. Nonetheless, many aspects of avian olfaction remain poorly understood. Our purpose was to broaden the knowledge about the importance of the sense of smell in some neglected bird groups: psittaciformes and ramphastids, and to compare how the response varied between the species. Because of the lack of information about the use of chemical cues for locating food in fruit-eating species, we also aimed to delve into this question. We conducted a 3-choice (water/vinegar/papaya and banana juice) scent test in 5 Costa Rican native species: scarlet macaw (Ara macao), red-lored amazon (Amazona autumnalis), yellow-naped amazon (Amazona auropalliata), keel-billed toucan (Ramphastos sulfuratus), and yellow-throated toucan (Ramphastos ambiguus). Results revealed that macaws and toucans allocated significantly more time to interacting with the fruit scent container, indicating that these species can perceive the volatile chemicals emitted by ripe fruits and that they can use this information to make foraging decisions. However, amazons did not dedicate more time to interact with the fruit treatment. Our research provides the first evidence of the ability to exploit chemical volatile cues in macaws and toucans.The experiments were performed in
accordance with the ethical standards of each institution
at which the studies were conducted, with Costa Rica animal welfare law n°7451/1994 and with the Spanish Government RD 53/201
Long-tailed pygmy rice rats modify their behavioural response and faecal corticosterone metabolites in response to culpeo fox but not to lesser grison
Even though behavioural and physiological reactions to predation risk exhibited by prey species have received considerable attention in scientific journals, there are still many questions still unsolved. Our aim was to broaden the knowledge on one specific question: do long-tailed pygmy rice rats adapt their behavioural and physiological antipredator strategies depending on the predator species? For this question, we live-trapped in a temperate forest in Southern Chile long-tailed pygmy rice rats (Oligoryzomys longicaudatus), which were exposed to three predator odour phases (Phase 0: preliminary, no predator cues; Phase 1: one plot with culpeo fox faeces (Lycalopex culpaeus), one plot with lesser grison (Galictis cuja) faeces and one plot acting as a control with no odour; Phase 2: post treatment, no predator cues). We measured the behavioural response by the capture ratio. To assess the physiological stress response, we collected fresh faecal samples to quantify faecal corticosterone metabolites (FCM). Our results showed that O. longicaudatus increased both the capture ratio and FCM levels in the presence of culpeo cues. Culpeo foxes have higher densities in the study area than G. cuja and exhibit a higher activity pattern overlap with O. longicaudatus. Moreover, it has been also been reported in other regions that L. culpaeus consumption of O. longicaudatus is more frequent compared to G. cuja diet. The increase in capturability could be because traps can be regarded as a shelter in high-risk settings, but it can also be explained by the predator inspection behaviour. The increase in FCM concentrations during culpeo treatment can be linked to the adaptive mobilisation of energy to execute antipredator responses to increase survival chance
Effect of intensity and duration of anthropic noises on European mink locomotor activity and fecal cortisol metabolite levels
Human activities involving noise emission can affect wild animals. European mink was exposed to road noise and human voice playbacks to analyze how sound intensity level and duration of both noises altered the time that individuals were active and if their fecal cortisol metabolite (FCM) levels varied. A Hierarchical Analysis Cluster was performed to establish 2 mink groups with respect to both noise source type: short duration/low intensity (SL) and long duration/high intensity (LH). We performed general linear mixed models to evaluate the variation in locomotor activity duration (s) and FCM (nanogram per gram) levels, respectively. The results showed both road noise and human voices decreased locomotor activity duration in SL more sharply compared with LH, and human voices were the triggers that induced the most pronounced response to both exposure conditions. FCM (ng/g) levels increased in SL compared with LH during road noise while the opposite happened during human voices. Differences based on sex and age of individuals were observed. In conclusion, noise characteristics given by the sound type determined the variations in locomotor activity duration while noise exposure level determined the variations in FCM (ng/g) levels. Attention should be paid to noisy activities (e.g., recreational activities for visitors in protected natural areas) and loud groups of people to conserve wildlife, especially noise sensitive specie
When food access is challenging: evidence of wood mice ability to balance energy budget under predation risk and physiological stress reactions
Prey species must balance the energetic cost of locomotion, foraging effort, and predation risk. In our work, we assessed how the
wood mice (Apodemus sylvaticus) balance these costs by manipulating food access difficulty and predation risk. Live trapping
was conducted in Madrid (Spain) where 80 Sherman traps were set in four different plots. To assess how wood mice manage their
energy budget, all traps were first subjected to a control period followed by four treatments of 3-day duration in which food access
was experimentally manipulated (free access, straw balls, straw balls wrapped in metal wire, opened plastic bottles, closed
bottles). Predation risk was simulated by exposing half of the traps to fox feces. To quantify food intake, we weighed the
remnants of food left by each captured mouse. Furthermore, we collected mouse fecal samples from traps to evaluate the
physiological stress response by quantifying fecal corticosterone metabolites (FCM). Results showed that despite mice generally
avoiding traps treated with fox feces, predation risk did not modulate food intake or FCM levels. By contrast, the experimental
manipulation of food access determined the amount eaten and increased FCM levels, probably owing to the different degrees of
difficulty and the energy required to obtain the food. Moreover, recaptured individuals ate more, indicating that experience
critically determines mice ability to reduce the costs of accessing food. By analyzing the joint variation between mice intake and
FCM levels depending on food restriction treatments, we found that mice were able to modulate their energetic expenditure
depending on food access difficulty probably in order to achieve a positive marginal value of energ